UNIVERSITY of OSLO SSS DEPARTMENT of PHYSICS Iu Ji 11 I
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N09300025 UNIVERSITY OF OSLO SSS DEPARTMENT OF PHYSICS REPORT SERIES iu Ji 11 i; (J ni _ U ..: LI NilJ^"J 1 JJJ iU il ,t i u,<Hil : ili ill Ih AM LI jjj Ui U-JJJ jjJIlfclfcifcifc.N We regret that some of the pages in the microfiche copy of this report may not be up to the proper legibility standards, even though'the best possible copy was used for preparing the master fiche SECTION for NUCLEAR PHYSICS AND ENERGY PHYSICS Annual Report January 1 — December 31 1992 UiO/PHYS/93-08 Received 19 - 04 - 1993 ISSN-0332-5571 O f* - - ^ "i - ? Contents 1 Introduction 5 2 Personel 6 2.1 Research Staff 6 2.2 Technical Staff 6 2.3 Visiting Scientists 7 2.4 Students 7 3 The Cyclotron 8 3.1 Operation and Maintenance 8 4 Data Acquisition and Analysis 9 4.1 Introduction 9 4.2 Configuration 10 4.3 Acquisition and Data Analysis Software 12 4.4 The CAMAC Pile-Up Rejection Module (PUR) 13 5 Nuclear Instrumentation 14 5.1 The CACTUS Project 14 5.2 The SIRI Strip Detector Project 15 5.3 The CHICSI Multifragment Detector 18 6 Experimental Nuclear Physics 21 6.1 Introduction 21 6.2 Nuclear Properties at Moderate Temperature 23 6.2.1 Extraction of Multiplicity Distributions 23 1 6.2.2 Spin Population in the 1MDy(3He,a)161Dy Reaction . 25 6.2.3 Nuclear Temperature in 3He Reactions 27 6.2.4 Level Densities in lMDy 28 6.2.5 Excitation Regions in 161Dy Feeding the Isotopes 161_IDy 30 6.2.6 Transferred Angular Momentum in the (3He,a) Reaction 31 6.2.7 Gamma-Ray Branching and the K Quantum Number in Even-Even Rare-Earth Nuclei 33 6.2.8 The K Quantum Number and the Decay of Neutron Resonances 34 6.2.9 Activities at NBI: Selective Studies of Hot Rotating Nuclei by Means of the Giant Dipole Resonance ... 37 6.2.10 Pre-Fission 7-Decay in Superheavy Nuclei 44 6.3 Rotational and High-Spin Nuclear Physics 48 6.3.1 Interpretation of Bands in 163Er within the Tilted Ro- tation Scheme 48 6.3.2 Delayed Crossing in the Unfavoured Signature Partner 163 of the h9/2[541]l/2- Band in Tm 50 6.3.3 Spectroscopy in the Odd-Odd Nucleus 162Tm 51 6.3.4 Angular Correlations in NORDBALL 52 6.3.5 Looking for M2 Admixtures in Sideband De-Excitations 53 6.3.6 High-Spin Study of 16SLu 53 6.3.7 High Spin States in 166Hf 55 6.3.8 Interpretation of the Rotational Band Structure in m,i72W The importance of Small Deformation Changes 56 6.3.9 Bandcrossings and the 71*13/3 Band in mRe 56 6.3.10 Octupole Deformed States in the Radium Region ... 57 6.3.11 Helium-Induced One-Neutron Transfer to Levels in 1MDy 58 6.4 High and Intermediate Energy Nuclear Physics 61 6.4.1 Isotopic Effects in Light Fragment Emission 61 6.4.2 Measurements of K+-Mesons at SIS 61 6.4.3 Strangeness Production in Ultrarelativistic Nucleus- Nucleus and Proton-Nucleus Collisions 62 2 7 Theoretical Nuclear Physics 66 7.1 The Nuclear Many-Body Problem and Nuclear Structure . 67 7.1.1 Studies of the Effective Interaction for Finite Nuclei . 67 7.1.2 The Structure of Neutron Deficient Sn Isotopes .... 68 7.1.3 Isobar Contributions to the Imaginary Part of the Optical-Model Potential for Finite Nuclei 71 7.1.4 New Equations of State for Neutron Stars 74 7.1.5 Model-Space Brueckner-Hartree-Fock Calculations for Nuclear Matter 76 7.1.6 Nuclear Renormalization of the Isoscalar Axial Cou- pling Constants 77 7.2 Nuclear Reactions 80 7.2.1 Momentum-Depeadent Mean Field Effects on the Nu- clear Equation of State and on Phase Transition Signals 80 7.3 The Foundation of Quantum Physics 81 7.3.1 Quantum Theory and Questions of Reality and Com- pleteness 81 7.3.2 SQUIDs as Macroscopic Quantum Objects 85 7.3.3 The Conception of Ether and Phenomena of Light - from Descartes to Einstein 86 8 Other Fields of Research 37 8.1 Radiation Physics 87 8.1.1 Instrumentation for Simultaneous 220Rn and 232Rn Mea- surements 87 8.1.2 221Rn and 226Ra in Tap Water from Drilled Wells ... 88 8.1.3 Influence of Meteorological Factors on the Radon Con- centration in Norwegian Dwellings 90 8.2 General Instrumentation 91 8.2.1 The Design of a Pure Pitch Automate for Keyboard Instruments 91 8.3 Energy Physics 92 8.3.1 Solar Hydrogen - Hydrogen Produced from Renewable Resources 92 8.3.2 PV-Driven Electrolysis 93 8.3.3 A Study of Heat-Exchange Properties of a New Semi- Open Solar Collector Concept 96 3 8.3.4 Photolysis- Hydrogen Produced Directly by Solar Ra- diation 99 8.3.5 The Possibility for Combined Quantum/Thermal Con- verters 100 8.3.6 The Importance of Insolation Autocorrelation in Solar Heat System Calculations 101 8.4 Neural Network 103 9 Seminars 105 10 Committees, Conferences and Visits 106 10.1 Committees and Various Activities 106 10.2 Conferences 108 11 Theses, Publications and Talks 110 11.1 Theses 110 11.2 Scientific Publications 110 11.2.1 Nuclear Physics and Instrumentation 110 11.2.2 Radiation Physics 112 11.2.3 Energy Physics 112 11.3 Scientific and Technical Reports 112 11.3.1 Nuclear Physics and Instrumentation 112 11.3.2 Energy Physics 115 11.3.3 Educational Physics 115 11.4 Scientific Talks 115 11.4.1 Nuclear Physics and Instrumentation 115 11.4.2 Energy Physics 120 11.4.3 Radiation 121 11.4.4 Educational Physics 121 11.5 Popular Science 121 11.6 Science Policy 124 4 Chapter 1 Introduction This annual report summarizes the research and development activities of the Section for Nuclear Physics and Energy Physics at The University of Oslo in 1992. It includes experimental and theoretical nuclear physics, as well as other fields of physics in which members of the section have participated. The report describes completed projects and work currently in progress. The experimental activities in nuclear physics are mainly centered around the Cyclotron Laboratory with the SCANDITRONIX MC-35 Cyclotron. Using the CACTUS riultidetector system, several experiments have been completed. Some results have been published while more data remains to be analyzed. The collaboration with foreign laboratories has continued in 1992. For many years we have participated in the Nordic collaboration, NORDBALL, at the Niels Bohr Tandem Accelerator Laboratory. Members of the section also participate in experiments at GSI, Darmstadt and GWC, Uppsala. At the end of 1992 13 students (for the degr*'« Cand. Scient.) and five post-graduate students (for the degree Dr. Scient.) were associated with the section. The cyclotron has continued to work satisfactorily due to the untiring effort of E. A. Olsen. The excellent job done by him, J. Wikne and J. Taylor in keeping the accelerator and data system in operation is highly appreciated by all of us. The basic costs of running the cyclotron laboratory is covered by the Uni- versity. The experimental activities, however, would not have been possible without the continued support from the Norwegian Research Council for Science and Humanities (NAVF). Finally, the efforts of Torgeir Engeland and Magne Guttormsen who have served as editors of this report, are appreciated by the other members of the Section. Blindern, March 1993 Svein Messelt Leader of the Section for Nuclear Physics and Energy Physics 5 Chapter 1 Personel 2.1 Research Staff Sven L. Andersen Senior scientist Harald Andås Research ass. (NAVF) Trond Bergene Research ass. (NAVF) Bård Bjerke Research ass. Torgeir Engeland Professor Ivar Espe Senior scientist Kristoffer Gjøtterud Assoc. prof. Magne Guttormsen Assoc. prof. Ole H. Herbjørnsen Assoc. prof. Morten Hjorth-Jensen Research ass. Anne Holt Research ass. Trygve Holtebekk Prof. emer. Finn Ingebretsen Professor Gunnar Løvhøiden Professor Svein Messelt Assoc. prof. (Section leader) Eivind Osnes Professor John Rekstad Professor Anders Storruste Senior scientist Roald Tangen Prof. emer. Per Olav Tjørn Professor Trine Spedstad Tveter Research assoc. (NAVF) 2.2 Technical Staff Eivind Atle Olsen Section engineer Jon Wikne Section engineer John Taylor Engineer ass. 6 2.3 Visiting Scientists Dunja Sultanovitc on leave from University of Sarajevo. 2.4 Students As of December 31,1992,13 graduate students (for the degree Cand. Scient.) and five post-graduate students (for the degree Dr. Scient.) were associated with the section. 7 Chapter 1 The Cyclotron 3.1 Operation and Maintenance E. A. Olsen, J. Wikne, J. Taylor and S. Messelt The beam line has been modified to make room for a target station close to the cyclotron. This has made it easier to obtain the beam intensity which has been asked for in connection with the astatine production. The total beam time used for nuclear experiments in 1992 was 332 hours with 3He beam. The time used for isotope production for the nuclear chemistry group was 16 hours with protons and 85 hours with alpha beam. Approximately four weeks have been used for scheduled and two weeks for unscheduled maintenance. 8 Chapter 1 Data Acquisition and Analysis 4.1 Introduction The data acquisition system at the Oslo Cyclotron Laboratory may be di- vided into two major components: • A front-end system responsible for data digitalization, read-out and formatting. This system is based on a VMEbus with connections to CAMAC and NIM devices. • A rear-end system used for on- and off-line analysis.